Physicochemical and molecular characterization of heavy metal–tolerant bacteria isolated from soil of mining sites in Nigeria

Abstract

Background Mining for precious metals is detrimental to the composition of soil structure and microbial diversity distribution and is a health risk to human communities around the affected communities. This study was aimed at determining the physical and chemical characteristics and diversity of bacteria in the soil of local mining sites for biosorption of heavy metals. Results Results of physical and chemical characteristics showed mean pH values and percentage organic carbon to range from 7.1 to 8.2 and 0.18 to 1.12% respectively with statistical significance between sampling sites (P ≤ 0.05). Similarly, cation exchange capacity, electrical conductivity, moisture, total nitrogen, and carbon/nitrogen ratio (C:N) in the soil ranged between 1.52 to 3.57 cmol/kg, 0.15 to 0.32 ds/m, 0.14 to 0.82%, 0.10 to 0.28%, and 1.7 to 4.8 respectively. The highest heavy metal concentration of 59.01 ppm was recorded in soils obtained from site 3. The enumeration of viable aerobic bacteria recorded the highest mean count of 4.5 × 106 cfu/g observed at site 2 with statistical significance (P ≤ 0.05) between the sampled soils. Alcaligenes faecalis strain UBI, Aeromonas sp. strain UBI, Aeromonas sobria, and Leptothrix ginsengisoli that make up 11.2% of total identified bacteria were able to grow in higher amended concentrations of heavy metals. The evolutionary relationship showed the four heavy metal–tolerant bacteria identified belonged to the phylum Proteobacteria of class Betaproteobacteria in the order Burkholderiales. Heavy metal biosorption by the bacteria showed Alcaligenes faecalis strain UBI having the highest uptake capacity of 73.5% for Cu. Conclusion In conclusion, Alcaligenes faecalis strain UBI (MT107249) and Aeromonas sp. strain UBI (MT126242) identified in this study showed promising capability to withstand heavy metals and are good candidates in genetic modification for bioremediation.

Persistence of a Wild-Type Virulent Aeromonas hydrophila Isolate in Pond Sediments from Commercial Catfish Ponds: A Laboratory Study

“…Isolates of A. sobria and another Aeromonas spp. collected from mining site soil in Nigeria displayed strong tolerance to lead (Pb), cadmium (Cd), copper (Cu), and chromium (Cr) at concentrations ≥ 6 mg L −1 [ 72 ]. Cai et al [ 26 ] noted that aeromonad populations positively correlate with temperature, nitrogen concentration, organic carbon load, and primary productivity.…”

Physiochemical analyses and molecular characterization of heavy metal-resistant bacteria from Ilesha gold mining sites in Nigeria

“…This could be attributed to the higher composition of anions in the water samples which were observed to be much higher than the WHO-recommended value, as well as the lower composition of cations which was also well below the recommended value [36]. For the soil samples, the EC values were observed to be much higher compared to the values reported by Ibrahim et al but much lower compared to the values reported by Edema et al in mining sites located in different geographical regions in Nigeria [27,37]. Spatial variation, varying intensities, and levels of gold mining activities could be the probable reason for this as this phenomenon also affects soil properties within the close range [27,38].…”

“…The bacterial colony count was determined by multiplying the number of counts with the dilution used and expressed as colony-forming units per milliliter (cfu/mL) of water and colony-forming units per gram (cfu/g) of soil [27].…”

Heavy Metal and Antibiotic Resistance in Bacteria from a Wastewater Treatment Plant

“…Numerous studies have looked at the isolation and characterization of heavy metal, and antibiotic-resistant bacteria in wastewater from places like the dumpsites (Sanuth and Adekanmbi, 2016), printeries (Adekanmbi et al, 2019), bight sediments (Timoney et al, 1978), lakes and rivers (Matyar et al, 2014), and many genera of bacteria have been discovered, including those isolated in this study. Multiple heavy metal and antibiotic resistance in Alcaligenes faecalis and Paenalcaligenes hominis from wastewater was reported by Abo-Amer et al (2015), Sanuth and Adekanmbi (2016), Adekanmbi et al (2019); Ayyal Al-Gburi (2020), Olowookere et al (2020) and Ibrahim et al (2021). According to a comparative analysis of Paenalcaligenes hominis 16S rRNA gene sequences, this bacterium shares <95 % similarity with all reported species of the Alcaligenaceae genera (Kämpfer et al, 2010).…”